The present invention relates to a crane vehicle with an overload safety unit, with a jib, preferably a telescoping jib, hinged to its superstructure which jib can be luffed by means of a luffing ram which is hinged to the jib and the superstructure, with extending sliding beams which are positioned at the end parts of the longitudinal sides of the carrier which face each other and which are provided at their ends with extending stabilizer bases, and with a unit measuring the swing angle of the jib the signals of which unit are fed to a processing unit of the overload safety unit, where the overload safety unit generates a warning signal and/or stops the crane operation when the crane reaches or exceeds limits which endanger its stability.
The stability of a crane vehicle with telescoping jib depends in addition to the size of the load hanging from the telescoping jib among other things on the luffing angle, the extension length of the telescoping jib, on the sag of the telescoping jib and in particular also on the angle of rotation of the superstructure with the telescoping jib relative to the carrier and on the stand rectangle defined by the stabilizer bases of the sliding beams. With regard to the stand rectangle defined by the extended sliding beams and stabilizer bases the stability of the crane is greatest when the jib points in the direction of the sliding beam extended the furthest. When the sliding beams are retracted and the stabilizer bases extended the stability is greater in the longitudinal direction of the carrier than in the direction of its transverse axis. The overload protection must therefore always take into account the extension state of the sliding beams, which is difficult to the extent that the stability also changes with different extension lengths of individual sliding beams.